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Endodontics · single question

Which root/canal has the HIGHEST reported incidence of containing an additional (second) canal?

  1. The mandibular second premolar
  2. A mandibular incisor
  3. The mesiobuccal root of the maxillary first molar (the 'MB2' canal)
  4. A maxillary canine
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Correct answer: C. The mesiobuccal root of the maxillary first molar (the 'MB2' canal)

The mesiobuccal root of the maxillary first molar is famous for harboring a second canal (MB2) at a high rate — reported incidence ranges widely by study/method (roughly 50-70%+ on average with CBCT/micro-CT), making it the classic 'most likely to have 2 canals' answer, and a frequent source of missed canals/endodontic failure if not specifically sought.

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